Posted: Fri, 3 Jun 2016 08:51 PM - 7,748 Readers
By: Marty Toohey - American-Statesman Staff
The storms that hit Central Texas this week weren’t as savage as forecasters had initially feared. But their effects will likely be felt along the Colorado River for days, if not weeks.
The river is dammed to create the Highland Lakes, six bodies of water that start at Lake Buchanan to the north and end at Lady Bird Lake in Austin. Those recently parched lakes are now full — more than full, really — with floodwater being pushed into Lake Travis and held there to minimize flooding in Austin and other communities downstream.
Forecasters expect rains to continue over the weekend, but even if they were to relent, water now flowing through creeks and streams would cause Lake Travis to continue rising, according to the Lower Colorado River Authority, the quasi-governmental agency that manages the lakes.
Lake Travis should creep up slightly well into Saturday, high enough to reach a few more homes in the Graveyard Point neighborhood, according to LCRA forecasts. Lake managers tentatively said they don’t expect the water to rise significantly higher, though the situation remains fluid.
“We’re waiting to see how intense this next round of rains is, and where it falls,” said John Hofmann, the LCRA’s manager of water operations.
Any new rain would be falling on ground that is already saturated. Much of Austin saw between 2 and 3 inches of rainfall over the past week, but some places farther upriver in the Hill Country saw nearly 7 inches.
This week’s rain prompted Austin and LCRA officials to ban boats on all of the Highland Lakes except for Buchanan. Boating on Lady Bird Lake is also banned until Monday.
The recent rains were part of a yearlong pattern that has turned Lake Travis from shriveled to swollen. It was about a third full in 2013, and not much higher in May 2015; the long, snaking body of water was shallow and skinny, with ’70s-era pop-top beer cans emerging along the shrinking shoreline and some lakeside businesses closing. In the year since, the region has seen the highest recorded rainfall total ever for that span of time: 59.61 inches.
LCRA data indicated that Lake Travis was at 116 percent of capacity as of Friday afternoon. That is an incomplete picture, though. Lake Travis was built partly to prevent the devastating floods that used to rage through Austin. When it reaches 100 percent full, just shy of 370 billion gallons, it can still add 256 billion gallons before it is truly full.
LCRA officials say they will limit the water stored in the “flood pool” because some low-lying homes sit within it. But those officials say the overriding consideration is keeping Austin and downstream communities from being flooded.
“That’s our insurance for Austin and downstream communities,” Hofmann said.
The idea of holding water in Lake Travis can seem odd when juxtaposed against the image this week of the numerous floodgates the LCRA opened along the Highland Lakes. Those gates are allowing more water through than usual.
But that’s actually a relatively small amount of water being sent downriver. Even with the floodwater being released from Lake Travis, U.S. River Forecast Center projections on Friday didn’t show flooding in places such as La Grange, Bastrop or Smithville, all of which saw significant flooding earlier this week.
Still, LCRA projections show floodwater stored in Lake Travis being released for weeks, with the amounts depending partly on rainfall. LCRA officials say they have experience striking a dammed-if-they-do, dammed-if-they-don’t balance between upstream and downstream communities.
“What’s happening downriver,” Hofmann said, “limits what we can put into the river.”